The present invention relates to a system and method for calculation of hazard levels of chemical/biological/nuclear agents in an environment, and more particularly to a method developed to generate hazard level indication in detectors of chemical, biological, or nuclear agents.
More in particular, the present invention relates to a technique developed to indicate the accumulated dosage that is hazardous to humans or other living organisms which estimates hazard level values by applying an exponentially weighted moving integration to measure the concentrations of the chemical/biological/nuclear agent in the environment. The system generates an indication of the level of hazard when the estimated hazard level values match or exceed empirically predetermined hazard dosage values for the agent in question.
Medical problems experienced by Armed Forces personnel has created a need to understand and provide warning when the level of accumulated dosage of a chemical, biological or nuclear agent reaches or exceeds the dosage level which would be harmful to the personnel exposed to the agent in question for a certain periods of time. Knowing the level of hazards for chemical/biological/nuclear agents would allow military commanders to change or adjust their operating procedures in order to prevent the personnel from exposure to harmful dosages of dangerous agents. There are no known algorithms that address the question of how to indicate the accumulated dosage of a chemical/biological/nuclear agent that may be hazardous to humans or other living organisms.
It is an object of the present invention to provide a technique of determining hazard levels of chemical/biological/nuclear agents in an environment and which warns a user when the accumulated dosage reaches or exceeds a hazard level.
It is another object of the present invention to provide an algorithm applicable to chemical, biological and nuclear detectors which would calculate accumulated dosage of an agent accumulated over a period of time, estimate hazard level values by applying an exponentially weighted moving integration to the measured concentrations of the detected chemical/biological/nuclear agent, and generate an indication of level of hazard when the estimated hazard level values match or exceed certain predetermined hazard dosage values determined empirically as harmful for the health of living organisms exposed to the agent in question.
The technique as herein described is directed to determining hazard levels and warning the users when the accumulated dosage of the chemical, biological or nuclear agent reaches the hazard levels and is envisioned to be applicable to any type of chemical, biological, or nuclear agent. According to the teaching of the present invention, a method of determining hazard levels of a vapor (chemical, nuclear, or biological agent) in an environment includes the steps of:
measuring concentrations of the agent in the environment;
estimating hazard level values of the agent by applying an exponentially weighted moving integration to the measured concentrations;
predetermining hazard dosage values defined empirically as harmful for living organisms;
comparing the estimated hazard level values to the predetermined hazard dosage values; and
generating an indication of the level of hazard when the estimated hazard level values match or exceed the empirically predefined hazard dosage values of the agent.
Preferably, the hazard dosage values are predetermined as falling in three dosage ranges, i.e., a low hazard dosage value, a medium hazard dosage value, and a high hazard dosage value, which for each chemical, biological or nuclear agent are represented by a corresponding value.
Essentially, an algorithm developed as a core of the present invention processes chemical vapor concentration measurements and generates chemical vapor hazard levels. This algorithm provides an estimate of hazard level values by using an exponentially weighted moving integration (further referred to herein as EWMI) of chemical vapor concentrations.
EWMI has important advantages over a standard moving integration:
(A) EWMI reduces the storage required to keep a history of the chemical vapor concentrations to one value per chemical vapor type; and,
(B) EWMI permits the automatic adjustment of the integration period and the decay rate for the accumulation of concentration as a function of the concentration level of the agent vapors.
The algorithm of the present invention uses EWMI to generate estimated detected agent hazard level values. When the EWMI calculated values match or exceeds the empirically set hazard levels the algorithm generates an indication of the level of the hazard.
The algorithm calculates the cumulative dosage according to the following equation:
Di=Dixe2x88x921+inixc2x7IST+D0,
wherein
Di=the cumulative dosage at the ith sample,
Dixe2x88x921=the dosage previous to the ith sample,
ini=the measured concentration at the ith sample,
IST=the independent sample time, and
D0=the initial value of the dosage.
The estimated hazard level values are calculated by the algorithm of the present invention according to:
DIi=DIixe2x88x921+inixc2x7ISTxe2x88x92TRixc2x7xe2x88x92DIixe2x88x921xc2x7IST
wherein
DIi=the exponentially weighted moving integral at the ith sample,
DIixe2x88x921=the exponentially weighted moving integral previous to the ith sample,
ini=the measured concentration at the ith sample,
IST=the independent sample time, and
TRi=the ith decay rate.
The decay rate TRi is calculated by estimating the time period necessary for a measured concentration to reach a next higher predetermined hazard dosage value.
These and other novel features and advantages of this invention will be fully understood from the following detailed description of the accompanying Drawings.